Contact roll for electrolytic tin lines



y 10 1 6 R. M. WlCK ET AL 2,754,485

CONTACT ROLL. FOR ELECTROLYTIC TIN LINES Filed Dec. 25, 1949 7Sheets-Sheet 1 HIH w I c 1, N

July 10, 1956 R w AL 2,754,485

CONTACT ROLL. FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7Sheets-Sheet 2 AZZOI'M July 10, 1956 R. M. WICK ET AL 2,754,485

CONTACT ROLL FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7Sheets-Sheet 3 g s E Q 0 w w S\ u] f 5 I13". 51. A p Q N a HerbertEIZI'WZ'JLU.

Aliornqy y 0, 1956 R. M. WlCK ET AL 2,754,485

CONTACT ROLL FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7Sheets-Sheet 4 III III Ill! Illllll lnvfe ziors J M W121 Herfierlfifiancisco.

15 $14. flag/g Attorney y 10, 1956 R. M. WlCK w AL 2,754,485

CONTACT ROLL FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7Sheets-Sheet 5 Herb 61% E fialzalls''o.

July 10, 1956 R. M. WICK ET AL 2,754,485

CONTACT ROLL FOR ELECTROLYTIC TIN LINES Filed Dec. 23, 1949 7Sheets-Sheet 6 R Inventors mzilm-d M Wm];

Herberi E lTralzczlsz'a y 0, 1956 R. M. WICK ET AL CONTACT ROLL FORELECTROLYTIC TIN LINES 7 Sheets-Sheet 7 Filed Dec. 23, 1949 NS Wm \m MNlluzmlors N Herfiert H. EQIZL'Z25'60.

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CONTACT RoLr. FOR nrsncrnorrrrc rrN LINES Application December 23, 1949,Serial No. 134,722

3 Claims. (Ci. 339--) This invention relates in general to electrolyticapparatus, and more particularly to a high-current contact roll andcollector head assembly for continuously electroplating metal strip.

The modern continuous electrolytic processes of plating steel strip withtin must necessarily operate at high speeds, and therefore at highcurrent inputs, to be commercially practical. it is the function of thecontact rolls to introduce ethciently the electric current into thestrip that is being electroplated. Each increase in speed will obviouslyshorten the plating period, and therefore require additional current,yet space and other considerations limit the number and size of contactrolls which can be profitably employed. It is therefore preferable toincrease the current input to each contact roll, up to the point Wherethe current-carrying capacity of the strip, rather than that of the rollassembly, becomes the limiting factor.

With a current input of 60,000 amperes to an electrolytic tin line, forexample, existing 12% diameter contact rolls have been required tohandle about 2,500 amperes each. The electrical demand for carrying eventhis load was not adequately met by the cross-section of the conductorelements used in the roll assembly, especialiy the shaft serving thedual function of support and electrical conductor, and excessive heatingwas the result.

A short brush life was also found to be characteristic f theconventional collector assemblies. This was true even when the brusheswere immersed in oil for more effective cooling. The need for frequentbrush adjustments and replacements, therefore, made the time and costrequired for maintenance extremely high. With oil immersion thereresults an excessive voltage drop at the brush contact surface.

From a mechanical standpoint, the usual roll bodies made of heavy walledpipe were always considerably. out of balance, resulting in substantialdrag and power waste and undue vibration even at very low speeds. Theuse of concentric forged cylinders for the rolls reduces vibration to aminimum, and has also produced a 25% decrease (spot reading) in thepower required to pull the strip through the plating unit.

The present improved contactor roll and collector assembly of the samesize, however, will handle in excess of 5,000 amperes without undueheating or any of these undesired conditions. Maintenance expense isreduced very substantially, largely because the brush life is muchlonger, being increased to several years. Since a set of brushes for aplating line is costly the value of this improvement is apparent.

One object of this invention, therefore, is to produce a contact rollassembly for electroplating strip which is characterized by very highcurrent carrying capacity and practically uniform voltage distributionacross the strip.

Another object is a balanced roll assembly which is substantially freefrom mechanical drag and vibration, and having extremely low maintenancecosts.

Another object is a contact roll assembly with integral end closureplates and arbor of steel, and with an inner conductive spindle andflange of copper.

Another object is a contact roll assembly provided with an externallyspirally grooved collector ring and air cooled brushes, and protectedagainst the effects of corrosive platin g atmospheres.

Still another object is a compact collector assembly which is completelyinterchangeable, easily removable, and exceptionally well insulatedelectrically, with a well protected and accessible bus-bar connectionand a ganged brush holder assembly affording improved conduction to thecollector ring.

Other and further objects, purposes and advantages of this inventionwill appear in the following detailed description, in the attached seven(7) sheets of drawings, and in the appended claims.

in the drawings: Fig. l is a transverse vertical section of thecollector assembly, taken on the line 1-1 of Fig. 2, with the currentintroducing end of the contact roll shown in broken section;

Fig. 2 is a vertical section on the line 22 of Fig. 1;

Fig. 3 is a side elevation of the contact roll, but with brushes andcollector assembly omitted;

Fig. 4 is a detail view showing the mounting of one of the brush holdersupport studs;

Fig. 5 is a detail view showing the attachment of one of the enclosurefastening rods;

Fig. 6 is a detail view of one of the support studs with brush holderand brush;

Fig. 7 is a vertical section taken on the line 7--7 of Fig. 1;

Fig. 8 is a vertical section on the line 8-8 of Fig.7;

Fig. 9 is a rear view of a modification of the collector assembly fromwhich the protective cover has been removed;

Fig. 10 is a side elevation of the collector assembly shown in Fig. 9but having the cover in place;

Fig. ll is an enlarged detail view of a ganged brush holder unit;

Fig. 12 is a vertical section taken substantially on the line l2-l2 ofFig. ll;

13 is a horizontal section on the line 1313 of Fig. 12; and

Fig. 14 is a detail view of the flexible ventilator hose connection.

Referring particularly to Figs. 1 and 3, the shell 1 of the contact rollis a hollow cylindrical forging, preferably of steel, and machinedinside and out for exact balance. A roll shell 1 /2" thick and 12%" inoutside diameter is sufiicient to carry the 5000 ampere current andproduc a voltage drop of less than .020 volt from the near to the farside of a 30" Wide strip contacting the roll. With the usual 18 distancebetween the point of tangency of strip and roll and the point ofintroduction of the strip into the solution, this means in practice asubstantially uniform voltage across the strip by virtue of equalizingcurrents within that distance. At each end the shell 1 is beveled as at2 and interiorly recessed as at 3 to provide a press fit with theintegral closure plates and arbors 4 and 5 which are also machined forproper balance and welded thereto as shown. As shown in Fig. 3, thecombined closure plate and arbor 4 consists of a single steel forging,the roll closure portion comprising a thick inner disc 6 and a beveledcollar portion 7 of the same outer diameter as the shell 1, and thearbor portion 8 being reduced and extended to form a bearing journal 9and an end portion 14 with a slotted keyway 11. The combined closureplate and arbor 5 is likewise an integral forging, with an inner discclosure portion 12 and beveled collar portion 13, and with an arborportion 14 having a bearing journal 15 and a reduced intermediateportion 16 and a further reduced end portion 17 and keyway 18.

of the collector assembly The arborportion 14 is, however, larger inoutside diameter thanthe corresponding arbor portion 8 on the other endof the roll, since it is centrally bored on its longitudinal axis as at19 (Fig. 1) to permit the introduction of a solid electrolytic coppercylindrical spindle 20 provided on its outer end with a conical taper 21and external threads 22. As the roll body is securely welded shut,'it isof the utmost importance that said current conductor spindle 24) bepermanently attached. This attachment is accomplished, in part, throughan annular copper conductor flange 23 Which is secured by the setbolts24 and lock washers 25 to the inner closure disc 12. The bore 19 of theroll closure plate and the corresponding portion of the copper spindle20 are mutually machined so as to afford a tight press fit within theclosure discQlZ and flange 23. Besides improving the electrical contact,this method of attachment provides mechanical stability and lessensvibrational stresses that mightpossibly tend to loosen the connectionbetween the spindle and the flange. The flange 23 is shrunk onto the.spindle end 26, which is important to give a mechanical and electricalconnection thatis substantially integral and permanent. Following theirassembly as indicated, the inner end of the spindle is peened over theflange as at {26,Qthus obtaining a further locking-in of the elementsand adding to the permanence of the electrical contact.

Any suitable bearing such as the ball bearing 27, mounted on supports 28on angles 29 forming the upper rim of the plating tank, may be used forsubstantially frictionless rotation of the journal 15. A similar hearing(not shown) is also required'for the journal 9 on the opposite end.

Referring further to Figs. 1 and 3, the peripherally slotted ring guard30 is a pressed fit on the reduced intermediate portion 16 of the arbor14. The tubular :copper collector head 31 is likewise a pressed fit onthe reduced end portion 17 of said arbor and the conically tapered endsection 21 of the inner copper spindle 20, being guarded againstseparate rotation by the key 32 in keyway'lS and by the washer 33 andnut 34 on the copper spindle threads 22 in the end recess 35 of thecollector head 31. The inner threads 36 in said end recess 35 permit theuse of a screwed-in pulling tool (not shown) to allow ready removal andreplacement of the copper spindle 20.

The outer surface of said collector head 31 is provided with a pluralityof continuous spiral grooves 37. Quintuple grooves of rectangular formabout 0.0 deep and wide with a pitch and 1%" lead have been found to beparticularly eflfective in providing an interruption of surface whichextraordinarily prolongs the life of the contacting brushes.

'In the assembly shown in Figs. 1 to 8 inclusive, the current ,flow intothe strip being electroplated is from the main bus bar (notshown) to thejumper bus 38 shown in Fig. 1 as attached by bolts 39 to the rectangularcopper conductor plate 40 and the copper distributing ring 41. Referringnow to Fig. 8, said distributing ring 41 is held tightly against thecircular steel backing plate 42 and spaced from the upright supportangle 43 by means of bolts 44 having insulating spacers 45, insulatingcollars 46 and outer insulating plates 47 of Synthane or .similarmaterial. From the copper distributing ring 41 the current is introducedinto six evenly spaced studs 48 thereon, each of which studs projectsparallel to the axis of the conductor roll and is held in properalignment by the cadmium-plated steel support ring'4 9. As shown in Fig.4, each stud 48 is provided with a tapered end portion 50 secured to thecopper ring 41 and the backing pl'ate 42 by the lock-washer 51 and nut52, and istapped at its other end to receive the small bolt 53 holdingit to the'support ring 49. Each stud 48 carries four brush-holders .54in each of which a spring 55 presses abrush 56 against thesurface of thecollector head While in 1 and 2 four brushholders 54 and four brushes56, are shown on each stud 48,01 a total of twenty-four of each for thecomplete apparatus, their number is obviously not critical, and may beincreased or decreased to correspond to the current demand.Brush-holders 54 are standard electrical equipment, being shown forexample in the United States patent to Bassett, No. 930,337, issuedAugust 10, 1909, and the accompanying 70% graphite-copper brushes are-also standard, hence require no further description. Current may evenbe fed into both ends of the roll, if desired, by simple duplication ofthe collector assemblies, but-the single ended arrangement shown willtransmit all the current the strip itself will carry, and has thefurther advantage of much greater compactness than double ended designs.

The drum-like welded metal cover 57, which may optionally be providedwith end and top sight windows 58 and 59 of Plexiglas or similartransparent plasticmaterial, is provided with a pair ofinner rod guides60, through which as shown inFig. 5 afastening rod 61 terminallythreaded as at 62 and having a Welded plate handle 63 and stop nut '64holds the cover to the copper ring 41 and backing plate 42.

T his enclosed collector assembly is kept under positive air pressurethrough the bottom air inlet pipe-65, which is secured by welded plate66 and rubber washer 67 as in Fig. 1. A clean air flow of the order of50 cubic feet per minute has been found normally suflicient for allcooling purposes. The low air demand is made possible by the favorableelectrical characteristics, including the low brush contact voltagedrop, by means of which the Waste heat generated is held to a lowfigure. This also provides assurance that the mechanism is wellprotected from the corrosive atmospheres characteristic of theenvironment around a production plating operation, since the air isvented through the space 68 between the ring guard 30 and the concentricand co-planar copper ring 41 and'back ing plate 42, in the direction ofthe plating tank and hence of the greatest concentration of corrosivefumes. The protection against dirt and corrosion thus afforded is asubstantial contributing element to reduced maintenance costs.

The major factor in prolonging the life of the brushes 56, however, isthe interrupted contact surface provided by the spiral grooves 37 on thecollector head 31. In the absence of such grooving, with a collectorhead otherwise the same and with the same brushes, operations undernormal loads resulted in such gross roughening of the collector surfaceas to preclude extended use. Upon the application of the grooving, theentire characteristic of mutual wear was altered. In a short time thecollector ring surface became smoother until it was coated with a glaze,presumably of graphite. Likewise the brushes wore smooth. The voltagedrop on passage of current between brush and collector surface wasreduced to the very low value of .040 volt, which is substantially lowerthan the least loss obtained previously.

Chromium plating the roll surface, and silver plating all the fixedcontacts between electrical current carrying members will improveoperations generally. The surface of the collector head 31, however,should be left unplated. Upon tests of a silver plated collector head itwas found that the silver soon coated the brushes, and when thisoccurred the contact was between silver and silver. The silver contactorsurface then roughened up and was soon abraded off, becoming apparent asafinesilverdust.

In the modification shown in Figs. 9 to 14 inclusive, the roll elementsremain the same, but the collector assembly is made more easilyremovable and interchangeable with other collector assemblies in aplating line, the brush holders arearranged in sub-assemblies of'gangedunits; the b u s-bar connections are removed from the zone of splashand'spray close to the plating cell and.-made' more accessible;.andthesinsulating and ventilating arrangements are somewhat changed.

Referring particularly to Figs. 9 and 10, the modified collectorassembly is mounted in alignment with the roll arbor 14 by means of thesupport brackets 68 and the angles 69 secured to the upper rim 29 of theplating tank at each side of the bearing 27. Elongated cross-slottedbolt-holes 70 in the angles 69, together with the bolts 71 and nuts 72,permit vertical and horizontal adjustments of said brackets relative tothe angles 69, to compensate for different collector assemblies. Whenproperly positioned the adjustment bolts 71 are tightened, and themounting may even be made more rigid if desired by tack welding theangles 69 together.

The round steel backing plate 73 is provided with four evenly spacedperipheral mounting lugs 74, which may either be made integral or weldedthereto in a jig for the uniformity of positioning required to assureperfectly interchangeable assemblies. Said lugs 74 are rigidly attachedby means of the mounting bolts 75 and 76 and insulators 77 to thesupport brackets 68. Moisture proof insulating members which aredesigned to support substantial loads, such as the Keystone Type EEinsulators, are preferable for this purpose.

Against the steel backing plate 73 is placed the heavy copper currentdistributing ring 78, which is provided with an outwardly and downwardlyextending integral lip 79. Said lip 79 is attached by the bolts 80,washers 81 and nuts 82 to the laminated jumper bus-bar 83, thuspermitting the connection to be made straight up from the main bus-bar(not shown), under the desirable conditions of more free working spaceand practically no spray contamination.

With reference to Figs. 11 to 13 inclusive, open terminal 84 on eachbrush lead or shunt 85 is firmly attached by means of a burred steelstud 86, nut 87 and washer 88 to the L-shaped copper bracket 89. Saidbracket is shaped to cover only a portion of one brush-holder 54,leaving ample space for the full swing of the spring pressure arm 90.Each group of four brush-holders 54 with their respective shunt brackets89, is mounted on a copper assembly tube 91, together with a largetapered contact bushing 92, and the ganged assembly is jig-aligned andbrazed together as a unit. To assist replacements when necessary ofsprings 55 and pressure arms 90, a full length holder pin 93 ispreferably used instead of individual holder pins, and is held in placeby the rings 49 and 78. Each unit is maintained in correct alignment bya locating pin 94 mounted into the distributing ring 78 and backingplate 73 and engaging in a hole 95 in the first shunt bracket, and issupported by means of a /4" bolt 96 or the like extending through thesteel support ring 49, end spacer 97, the center of assembly tube 91,and said distributing ring 78 and backing plate 73, terminating with awasher 98 and nut 99 at the rear side of the backing plate 73.

It will be noted that the radial positions of the brushholders 54 inFig. 9 are modified somewhat from those in Fig. 2, primarily for addedaccessibility to the brush shunt connections. Lateral offsetting orstaggering of alternate brush holder units, by inch for example, is alsodesirable and may be accomplished by using three sets of such units withA; inch long tapered bushings and inch end spacers, and three sets withA3 tapered bushings and inch spacers.

The cover 57 and its securing means are substantially as previouslydescribed. The air inlet connection, however, has been relocated to oneside of the bus bar connection, and is made by means of a length offlexible ventilation hose 1'90 having a bayonet type connector 191 tothe cover which permits ready removal, as shown in Fig. 14.

When it is desired to remove the cover 57, the endthreaded rods 61 arewithdrawn, the flexible hose 100 is detached from the cover, and thehose may then be swung clear of the collector assembly to give more freeworking space. Removal and replacement of any brush holder unit at theline without interfering with the remaining five holders or the outersupport ring 49, may be done by removing the center bolt 96 and the endspacer 97 and pulling the unit toward the support ring 49 until it isdisengaged from its socket 102 in the distributing ring 78 and thelocating pin 94, when it can be raised free of the collector assemblyand a replacement unit re-installed by reversing the procedure. Theentire assembly can be disconnected from the line by removing the fourmounting bolts 75' from the insulators 77 and the three bus-barattaching bolts 80, and a substitute assembly aligned and re-connected.It is thus possible to make repairs or replacements with a minimum ofdisassembly of contacts or joints.

To summarize the functional aspects of this invention, it is to be notedthat all the mechanical and electrical requirements have been met so asto achieve substantially vibrationless operation, very nominal bending,adequate strength and rigidity, low voltage losses in collecting andtransmitting the current, and remarkably long brush life and freedomfrom maintenance at very high currents and high strip speeds.

Although we have hereinabove shown and described this invention inconsiderable detail, we do not wish to be limited to the exact andspecific details of the construction so shown and described, but we mayalso use such substitutions, modifications, or equivalents thereof asare embraced within the scope and spirit of the invention, or as arepointed out in the appended claims.

We claim:

1. A collector device for supplying current to a horizontally disposedplating roll having an outwardly extending contact portion, comprising apair of upright support brackets adjustably mounted adjacent saidcontact portion, a plurality of insulating members mounted on saidsupport brackets, a backing plate removably secured to said insulatingmembers, a distributing ring thereagainst concentric with said rollcontact portion and having an extended portion adapted for connection tocurrent source, an outer support ring in axially spaced parallelrelation to the distributing ring, and a plurality of radially arrangedganged brush units interposed between and supported by said distributingand outer support rings.

2. in the combination described in claim 1, each ganged brush unitcomprising an assembly tube; a contact bushing and a plurality ofalternately disposed brush-holders and shunt brackets on said tube andmade integral therewith as by brazing; brushes in said brush-holderswith their shunts connected to the shunt brackets; an end spacer alignedwith the assembly tube; a bolt extending through the outer support ring,the end spacer, the assembly tube, the distribution ring and the backingplate, and holding them in unitary relationship; and a locating pinmounted in the distributing ring and backing plate and engaging in ahole in the first shunt bracket.

3. A collector device for supplying current to a plating roll having anextended contact portion, comprising a backing plate, a currentdistributing ring thereagainst concentric with the contact portion andhaving a plurality of radially s aced tapered sockets, an outer supportring in axially spaced relation to the current distributing ring andhaving a plurality of bolt holes in alignment with the sockets, and aplurality of brush units interposed between said spaced rings, eachbrush unit comprising a conductive assembly tube; a taperedsocket-engaging contact bushing and a plurality of alternately disposedbrushholders and shunt brackets mounted on said tube and brazed theretoas a unit; a single spring holder rod extending through saidbrush-holders; brushes in said brushholders having their shuntsindividually connected to said brackets; an end spacer aligned with saidtube; and a bolt extending through a bolt-hole in the outer supportring,

References Cited in the file ofthis patent Watson Dec. 16, 1941 UNITEDSTATES PATENTS Apple Feb. 2, 1915 Hobart "Feb. 24, 19 31 Hague et alFeb.,1, 1938 10 .Hague et al Oct. 25, 1938 .18 Hollander m Ian. 16, 1943 Mu'ddiman-et a1 A pr.'2 0, 1943 'Na'chtman AIgg..10,1 9. 4 8'Sprague Aug. 10,1948 Powers 'July 4, 1950 'Winterhalter Oct. 17, f 1950Cooper-et a1 Nov. 20, 1951 FOREIGN PATENTS Germany Feb. 11, 1909

